Why Intelligent People Drink More Alcohol

Drinking alcohol is evolutionarily novel, so the Hypothesis would predict that more intelligent people drink more alcohol than less intelligent people.

The human consumption of alcohol probably originates from frugivory (consumption of fruits). Fermentation of sugars by yeast naturally present in overripe and decaying fruits produces ethanol, known to intoxicate birds and mammals. However, the amount of ethanol alcohol in such fruits ranges from trace to 5%, roughly comparable to light beer. (And you can't really get drunk on light beer.) It is nothing compared to the amount of alcohol present in regular beer (4-6%), wine (12-15%), and distilled spirits (20-95%).

Human consumption of alcohol, however, was unintentional, accidental, and haphazard until about 10,000 years ago. The intentional fermentation of fruits and grain to yield ethanol arose only recently in human history. The production of beer, which relies on a large amount of grain, and that of wine, which similarly requires a large amount of grapes, could not have taken place before the advent of agriculture around 8,000 BC and the consequent agricultural surplus. Archeological evidence dates the production of beer and wine to Mesopotamia at about 6,000 BC. The origin of distilled spirits is far more recent, and is traced to Middle East or China at about 700 AD. The word alcohol - al kohl - is Arabic in origin, like many other words that begin with "al," like algebra, algorithm, alchemy, and Al Gore.

Human experience with concentrations of ethanol higher than 5% that is attained by decaying fruits is therefore very recent. More importantly, any unintentional, accidental, and haphazard consumption of alcohol in the ancestral environment, before the advent of agriculture about 10,000 years ago, happened as a result of eating, not drinking, whereas alcohol is almost entirely consumed today by drinking, not eating. (Deep-fried beer is a very recent exception.) The Hypothesis would therefore predict that more intelligent individuals may be more likely to prefer drinking modern alcoholic beverages (beer, wine, and distilled spirits) than less intelligent individuals, because the substance and the method of consumption are both evolutionarily novel.

Consistent with the prediction of the Hypothesis, more intelligent children, both in the United Kingdom and the United States, grow up to consume alcohol more frequently and in greater quantities than less intelligent children. Controlling for a large number of demographic variables, such as sex, race, ethnicity, religion, marital status, number of children, education, earnings, depression, satisfaction with life, frequency of socialization with friends, number of recent sex partners, childhood social class, mother's education, and father's education, more intelligent children grow up to drink more alcohol in the UK and the US.

The following graph shows the association between childhood intelligence (grouped into five "cognitive classes": "very dull" - IQ < 75; "dull" - 75 < IQ < 90; "normal" - 90 < IQ < 110; "bright" - 110 < IQ < 125; "very bright" - IQ > 125) and the latent factor for the frequency of alcohol consumption. The latter variable is constructed from a large number of indicators for the frequency of alcohol consumption throughout adult life and standardized to have a mean of 0 and a standard deviation of 1.0. The data come from the National Child Development Study (NCDS) in the United Kingdom. There is a clear monotonic association between childhood intelligence (measured before the age of 16) and the frequency of alcohol consumption in their 20s, 30s, and 40s. "Very bright" British children grow up to consume alcohol nearly one full standard deviation more frequently than their "very dull" classmates.

The following graph shows the association between childhood intelligence and the latent factor for the quantity of adult alcohol consumption decades later among the British NCDS respondents. Once again, there is a clear monotonic association between childhood intelligence and the quantity of adult alcohol consumption. "Very bright" British children grow up to consume nearly eight-tenths of a standard deviation more alcohol than their "very dull" classmates.

The following graph shows the association between childhood intelligence, measured in junior high and high school, and adult alcohol consumption seven years later in the National Longitudinal Study of Adolescent Health (Add Health) data in the United States. The association is clear and nearly monotonic. The more intelligent Americans are in their childhood, the more alcohol they consume as young adults.

It is important to note that both income and education, as well as childhood social class and parents' education, are controlled in multiple regression analyses of these data from the US and the UK. It means that it is not because more intelligent people occupy higher-paying, more important jobs that require them to socialize and drink with their business associates that they drink more alcohol. It appears to be their intelligence itself, rather than correlates of intelligence, that inclines them to drink more.